The Experts below are selected from a list of 39393 Experts worldwide ranked by ideXlab platform
Bin Zhang - One of the best experts on this subject based on the ideXlab platform.
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experimental study on the width of the reasonable segment pillar of the extremely soft coal seam in the deep mine
Geotechnical and Geological Engineering, 2019Co-Authors: Bo Wang, Fuxing Jiang, Chao Wang, Bin ZhangAbstract:Various dynamic disasters will happen in the extremely soft coal seam mining process of Gob-side entry in the deep mine, including large Deformation of roadways, Rock burst, gas unusual, floor water invasion, spontaneous combustion of coal seam and so on. Therefore, a reasonable segment pillar will not only avoid the dynamic disasters in the excavating process, but also improve the resource utilization. Taking the goaf working face of extremely soft coal seam in the deep mine in one particular mine of Shandong Province as the engineering example, this paper first analyzes optional locations of the gob-side entry, finding that the gob-side entry should be located in the low stress block and it’s the most favorable to keep small pillars and goafs isolated. Then, it is found that small surrounding Rock Deformation of gob-side entry takes place in the driving process through the numerical simulation, and the Deformation will increase with the increasing width of the chain pillar. The surrounding Rock Deformation of gob-side entry increases in the stoping stage. Small width of the chain pillar will easily result in the instability of the roadway. As the swivel angle of the basic roof increases, the surrounding Rock Deformation of gob-side entry will accordingly increase. Finally, the numerical calculation and on-spot mine pressure monitoring illustrate that the width of the segment pillar in the gob-side entry should be 5–7 m, with 6 m the best.
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model test study on surrounding Rock Deformation and failure mechanisms of deep roadways with thick top coal
Tunnelling and Underground Space Technology, 2015Co-Authors: Qi Wang, Baofa Jiang, Dechao Wang, Hanbin Wang, Bin Zhang, Guoqiang RuanAbstract:Abstract The deep roadway with thick top coal is a typical roadway difficult to support in deep mining project, and resolving this sophisticated problem to control the stability of surrounding Rock is of great significance in safety production of coal mines. In order to explore the surrounding Rock Deformation and failure mechanisms of such deep roadways, with Zhaolou coal mine in Juye mining area of China as the engineering background, a large-scale geomechanical model test was carried out. The displacement and stress evolution laws of surrounding Rock supported by the pressure relief anchor box beam system were researched. Meanwhile, the related results validate and analyze main failure characteristics and mechanisms of the surrounding Rock by comparing with field test.
Cristiano Collettini - One of the best experts on this subject based on the ideXlab platform.
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the role of fluid pressure in induced vs triggered seismicity insights from Rock Deformation experiments on carbonates
Scientific Reports, 2016Co-Authors: M M Scuderi, Cristiano CollettiniAbstract:Fluid overpressure is one of the primary mechanisms for tectonic fault slip, because fluids lubricate the fault and fluid pressure reduces the effective normal stress that holds the fault in place. However, current models of earthquake nucleation, based on rate- and state- friction laws, imply that stable sliding is favoured by the increase of pore fluid pressure. Despite this controversy, currently, there are only a few studies on the role of fluid pressure under controlled, laboratory conditions. Here, we use laboratory experiments, to show that the rate- and state- friction parameters do change with increasing fluid pressure. We tested carbonate gouges from sub hydrostatic to near lithostatic fluid pressure conditions, and show that the friction rate parameter (a − b) evolves from velocity strengthening to velocity neutral behaviour. Furthermore, the critical slip distance, Dc, decreases from about 90 to 10 μm. Our data suggest that fluid overpressure plays an important role in controlling the mode of fault slip. Since fault rheology and fault stability parameters change with fluid pressure, we suggest that a comprehensive characterization of these parameters is fundamental for better assessing the role of fluid pressure in natural and human induced earthquakes.
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a novel and versatile apparatus for brittle Rock Deformation
International Journal of Rock Mechanics and Mining Sciences, 2014Co-Authors: Cristiano Collettini, Giuseppe Di Stefano, B M Carpenter, Piergiorgio Scarlato, Telemaco Tesei, Silvio Mollo, Fabio Trippetta, Chris MaroneAbstract:Abstract This paper describes a new biaxial Rock Deformation apparatus within a pressure vessel, consisting of a stainless steel vessel with an internal diameter of 40 cm and six main access ports for electronics (~100 pins), pore fluids (three lines), and confining oil. The apparatus has to ability to work on large Rock samples, up to 20×20 cm 2 , with horizontal and vertical forces up to 1.5 MN. The maximum confining pressure of the vessel is 70 MPa, and fluid flow properties and permeability of large-samples can be tested using up to 8 L of fluids that can be pressurized up to 30 MPa. Sliding velocity during experiments is in the range 0.1 m/s – 1.0 cm/s. The machine stiffness is 0.91 kN/μm and 1.3 kN/μm for the vertical and horizontal axes, respectively. Measurements on friction, velocity dependence of friction and healing properties of reference material like granite and talc replicate the values presented in the literature. Triaxial stress state tests with controlled confining and pore fluid pressure, and fluid flow through the samples have been performed successfully. The machine is extremely versatile, as it works as a uniaxial, triaxial or true-triaxial apparatus, on Rock samples with dimensions ranging from several to tens of centimetres. Due to the broad number of potential operating conditions, we decided to name the machine BRAVA: Brittle Rock Deformation Versatile Apparatus.
Valentin Gischig - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of helium and argon release during fluid-pressure- triggered Rock Deformation
Scientific Reports, 2020Co-Authors: Clément Roques, Ulrich Weber, Bernard Brixel, Hannes Krietsch, Nathan Dutler, Matthias Brennwald, Linus Villiger, Joseph Doetsch, Mohammadreza Jalali, Valentin GischigAbstract:Temporal changes in groundwater chemistry can reveal information about the evolution of flow path connectivity during crustal Deformation. Here, we report transient helium and argon concentration anomalies monitored during a series of hydraulic reservoir stimulation experiments measured with an in situ gas equilibrium membrane inlet mass spectrometer. Geodetic and seismic analyses revealed that the applied stimulation treatments led to the formation of new fractures (hydraulic fracturing) and the reactivation of natural fractures (hydraulic shearing), both of which remobilized (He, Ar)-enriched fluids trapped in the Rock mass. Our results demonstrate that integrating geochemical information with geodetic and seismic data provides critical insights to understanding dynamic changes in fracture network connectivity during reservoir stimulation. The results of this study also shed light on the linkages between fluid migration, Rock Deformation and seismicity at the decameter scale.
Shicheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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coupled thermo hydro mechanical chemical modeling of water leak off process during hydraulic fracturing in shale gas reservoirs
Energies, 2017Co-Authors: Fei Wang, Yichi Zhang, Shicheng ZhangAbstract:The water leak-off during hydraulic fracturing in shale gas reservoirs is a complicated transport behavior involving thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes. Although many leak-off models have been published, none of the models fully coupled the transient fluid flow modeling with heat transfer, chemical-potential equilibrium and natural-fracture dilation phenomena. In this paper, a coupled thermo-hydro-mechanical-chemical (THMC) model based on non-equilibrium thermodynamics, hydrodynamics, thermo-poroelastic Rock mechanics, and non-isothermal chemical-potential equations is presented to simulate the water leak-off process in shale gas reservoirs. The THMC model takes into account a triple-porosity medium, which includes hydraulic fractures, natural fractures and shale matrix. The leak-off simulation with the THMC model involves all the important processes in this triple-porosity medium, including: (1) water transport driven by hydraulic, capillary, chemical and thermal osmotic convections; (2) gas transport induced by both hydraulic pressure driven convection and adsorption; (3) heat transport driven by thermal convection and conduction; and (4) natural-fracture dilation considered as a thermo-poroelastic Rock Deformation. The fluid and heat transport, coupled with Rock Deformation, are described by a set of partial differential equations resulting from the conservation of mass, momentum, and energy. The semi-implicit finite-difference algorithm is proposed to solve these equations. The evolution of pressure, temperature, saturation and salinity profiles of hydraulic fractures, natural fractures and matrix is calculated, revealing the multi-field coupled water leak-off process in shale gas reservoirs. The influences of hydraulic pressure, natural-fracture dilation, chemical osmosis and thermal osmosis on water leak-off are investigated. Results from this study are expected to provide a better understanding of the predominant leak-off mechanisms for slickwater fracturing-fluids in hydraulically fractured shale gas reservoirs.
Kervyn M. - One of the best experts on this subject based on the ideXlab platform.
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Structural and geochemical interactions between magma and sedimentary host Rock: the Hovedøya case, Oslo Rift, Norway
'American Geophysical Union (AGU)', 2020Co-Authors: Poppe Sam, Galland Olivier, Winter Niels, Goderis Steven, Claeys Philippe, Boulvais Philippe, Kervyn M.Abstract:International audienceTwo end‐member conceptual models are used to describe Deformation of the Earth's crust induced by magma intrusion. “Mode I” fracturing assumes tensile, or opening‐mode, elastic Deformation, while “Mode II” fracturing assumes plastic shear‐mode Deformation around a viscous indenter. Field observations of both mechanisms exist, but it remains unclear which mechanism dominates in which conditions. We describe intrusion geometries, host Rock Deformation and geochemical magma‐host Rock interactions around 53 exceptionally preserved, tephrite‐basanite Permian dike segments of 0.5‐30 cm thickness. These thin dikes, i.e. ‘dikelets’, intruded Late‐Ordovician carbonate‐rich sedimentary Rocks on Hovedøya island, Oslo Rift, Norway. Dikelets emplaced in pre‐existing fractures dominantly created cavities ahead of their narrow, tapering tips, and are associated with bent host Rock, broken bridges and stepped segmented geometries. Other tips are blunt with dense brittle fracturing around them. Also, cross‐sectional intrusion segment opening profiles deviate from parabola‐shaped profiles typical for elastic media. The observations demonstrate that dominant opening‐mode host Rock Deformation can co‐exist with shear‐mode Deformation locally. Alignment of most dikelet segments along the dominant host Rock fracture directions highlights the control of local structural orientations on magma emplacement. Analysis of bulk major and trace element compositions, in‐situ micro‐XRF sample analysis and carbon and oxygen stable isotope compositions suggest that thermo‐chemical interactions between magma and the carbonate‐rich host Rock produced a low‐viscosity mixture of magma, pore water and gas. We propose that such low‐viscosity hybrid fluid may assist in the intrusion of magma in sedimentary Rocks by filling the cavity ahead of propagating sheet intrusion tips
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Structural and Geochemical Interactions Between Magma and Sedimentary Host Rock : The Hovedøya Case, Oslo Rift, Norway
2020Co-Authors: Poppe S., Galland O., De Winter N. J., Goderis S., Claeys P., Boulvais P., Kervyn M.Abstract:Two end-member conceptual models are used to describe Deformation of the Earth's crust induced by magma intrusion. “Mode I” fracturing assumes tensile or opening-mode, elastic Deformation, while “Mode II” fracturing assumes plastic shear-mode Deformation around a viscous indenter. Field observations of both mechanisms exist, but it remains unclear which mechanism dominates in which conditions. We describe intrusion geometries, host Rock Deformation, and geochemical magma-host Rock interactions around 53 exceptionally preserved, tephrite-basanite Permian dike segments of 0.5- to 30-cm thickness. These thin dikes, that is, “dikelets,” intruded Late-Ordovician carbonate-rich sedimentary Rocks on Hovedøya island, Oslo Rift, Norway. Dikelets emplaced in preexisting fractures dominantly created cavities ahead of their narrow, tapering tips and are associated with bent host Rock, broken bridges, and stepped segmented geometries. Other tips are blunt with dense brittle fracturing around them. Also, cross-sectional intrusion segment opening profiles deviate from parabola-shaped profiles typical for elastic media. The observations demonstrate that dominant opening-mode host Rock Deformation can coexist with shear-mode Deformation locally. Alignment of most dikelet segments along the dominant host Rock fracture directions highlights the control of local structural orientations on magma emplacement. Analysis of bulk major and trace element compositions, in situ micro-XRF sample analysis and carbon and oxygen stable isotope compositions, suggests that thermochemical interactions between magma and the carbonate-rich host Rock produced a low-viscosity mixture of magma, pore water, and gas. We propose that such low-viscosity hybrid fluid may assist in the intrusion of magma in sedimentary Rocks by filling the cavity ahead of propagating sheet intrusion tips
